Aluminum nitride thin films for high frequency smart ultrasonic sensor systems

Investigations were carried out on the usability of aluminum nitride thin films for the manufacturing of ultrasound transducers by the use of sensor test structures. Some design considerations were performed for different sensor designs, electrode size variations and substrate materials in this work. It could be shown that the electrode size can be smaller than 1 mm square for use as high frequency sensors. Different substrate materials are principle usable, like e.g. silicon, aluminum oxide or quartz. Additional tests showed that these sensors can also be used for high temperature application up to 200 °C. The reason is the very good temperature resistance of the AlN thin films.